diff --git a/modules/audio_processing/aec3/render_buffer.cc b/modules/audio_processing/aec3/render_buffer.cc
index 60ea69cce1..aa511e2b6b 100644
--- a/modules/audio_processing/aec3/render_buffer.cc
+++ b/modules/audio_processing/aec3/render_buffer.cc
@@ -42,8 +42,9 @@ void RenderBuffer::SpectralSum(
   int position = spectrum_buffer_->read;
   for (size_t j = 0; j < num_spectra; ++j) {
     for (const auto& channel_spectrum : spectrum_buffer_->buffer[position]) {
-      std::transform(X2->begin(), X2->end(), channel_spectrum.begin(),
-                     X2->begin(), std::plus<float>());
+      for (size_t k = 0; k < X2->size(); ++k) {
+        (*X2)[k] += channel_spectrum[k];
+      }
     }
     position = spectrum_buffer_->IncIndex(position);
   }
@@ -60,18 +61,18 @@ void RenderBuffer::SpectralSums(
   size_t j = 0;
   for (; j < num_spectra_shorter; ++j) {
     for (const auto& channel_spectrum : spectrum_buffer_->buffer[position]) {
-      std::transform(X2_shorter->begin(), X2_shorter->end(),
-                     channel_spectrum.begin(), X2_shorter->begin(),
-                     std::plus<float>());
+      for (size_t k = 0; k < X2_shorter->size(); ++k) {
+        (*X2_shorter)[k] += channel_spectrum[k];
+      }
     }
     position = spectrum_buffer_->IncIndex(position);
   }
   std::copy(X2_shorter->begin(), X2_shorter->end(), X2_longer->begin());
   for (; j < num_spectra_longer; ++j) {
     for (const auto& channel_spectrum : spectrum_buffer_->buffer[position]) {
-      std::transform(X2_longer->begin(), X2_longer->end(),
-                     channel_spectrum.begin(), X2_longer->begin(),
-                     std::plus<float>());
+      for (size_t k = 0; k < X2_longer->size(); ++k) {
+        (*X2_longer)[k] += channel_spectrum[k];
+      }
     }
     position = spectrum_buffer_->IncIndex(position);
   }